The ability to accurately measure electrical conductivity in bulk materials is required in many different fields and in particular this ability is required for measuring electrical conductivity in materials having a low electrical conductivity. One example is the food industry wherein electrical conductivity is measured to determine and/or investigate characteristics of foodstuffs. For example, techniques for measuring the electrical conductivity of milk have been employed to investigate both the physical chemistry of milk and the growth of bacteria therein.
McPhillips, J. & Snow, N. (1958), “Studies on Milk with a New Type of Conductivity Cell”, The Australian Journal of Dairy Technology pp. 192-196 discloses an electrical arrangement for performing such measurements in relation to milk and Gupta, S. & Hills, G. (1956), “A Precision Electrode-less Conductance Cell for use at Audio Frequencies” discloses a similar electrical arrangement. Both arrangements comprise a current loop coupled between an energising circuit and a sensing circuit via two toroidal transformers.
However, these arrangements are unsuitable for various applications such as vat applications because the material being measured fouls and blocks the current loop, which further causes problems when the vat has to be cleaned.
Another problem with these arrangements is that they suffer from supply energisation fluctuations, which cause measurement noise and require stabilisation of the power supply and supply voltage monitoring.
Hence, there is a need for a system and/or method and/or apparatus for accurately measuring electrical conductivity that addresses or at least ameliorates the aforementioned problems. In particular, such a system, method and/or apparatus is required for measuring electrical conductivity in materials having a low electrical conductivity.
In this specification, the terms “comprises”, “comprising” or similar terms are intended to mean a non-exclusive inclusion, such that a method, system or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed.